The present invention relates to a system for controlling a movable member such as a window or door and, more particularly, to a motor-driven system for controlling opening/closing of a window of an automobile or the like.
A known conventional automobile window automatic motor-driven opening/closing system includes an electric motor for driving a window so as to open/close the window, a pressure responsive sensor arranged in association with the window, a detector circuit, coupled to the pressure responsive sensor, for detecting an squeezed object (typically, a part of a human body such as a hand) caught in a way of the window during a closing operation of the window, and a control circuit, coupled to the detector circuit, for controlling the electric motor in response to the squeezed object in such a direction to open the window, thereby releasing the object from the window.
Such a conventional system, however, is unsatisfactory for the following reason. That is, response characteristics of the pressure responsive sensor change in accordance with its installation position of a window frame. An output from the pressure responsive sensor depends on a pressure on the pressure responsive sensor. The characteristics of the pressure responsive sensor are changed or degraded by aging. The detector circuit easily erroneously operates.
For example, even though a squeezed object is present, the detector circuit does not detect the object. To the contrary, the detector circuit erroneously detects a squeezed object although nothing is squeezed.
Therefore, a demand has arisen for a motor-driven window/door system with high reliability and safety.